[mirror_ubuntu-jammy-kernel.git] / kernel / kcsan / kcsan.h

/* SPDX-License-Identifier: GPL-2.0 */

/*
 * The Kernel Concurrency Sanitizer (KCSAN) infrastructure. For more info please
 * see Documentation/dev-tools/kcsan.rst.
 */

#ifndef _KERNEL_KCSAN_KCSAN_H
#define _KERNEL_KCSAN_KCSAN_H

#include <linux/atomic.h>
#include <linux/kcsan.h>
#include <linux/sched.h>

/* The number of adjacent watchpoints to check. */
#define KCSAN_CHECK_ADJACENT 1
#define NUM_SLOTS (1 + 2*KCSAN_CHECK_ADJACENT)

extern unsigned int kcsan_udelay_task;
extern unsigned int kcsan_udelay_interrupt;

/*
 * Globally enable and disable KCSAN.
 */
extern bool kcsan_enabled;

/*
 * Save/restore IRQ flags state trace dirtied by KCSAN.
 */
void kcsan_save_irqtrace(struct task_struct *task);
void kcsan_restore_irqtrace(struct task_struct *task);

/*
 * Initialize debugfs file.
 */
void kcsan_debugfs_init(void);

/*
 * Statistics counters displayed via debugfs; should only be modified in
 * slow-paths.
 */
enum kcsan_counter_id {
	/*
	 * Number of watchpoints currently in use.
	 */
	KCSAN_COUNTER_USED_WATCHPOINTS,

	/*
	 * Total number of watchpoints set up.
	 */
	KCSAN_COUNTER_SETUP_WATCHPOINTS,

	/*
	 * Total number of data races.
	 */
	KCSAN_COUNTER_DATA_RACES,

	/*
	 * Total number of ASSERT failures due to races. If the observed race is
	 * due to two conflicting ASSERT type accesses, then both will be
	 * counted.
	 */
	KCSAN_COUNTER_ASSERT_FAILURES,

	/*
	 * Number of times no watchpoints were available.
	 */
	KCSAN_COUNTER_NO_CAPACITY,

	/*
	 * A thread checking a watchpoint raced with another checking thread;
	 * only one will be reported.
	 */
	KCSAN_COUNTER_REPORT_RACES,

	/*
	 * Observed data value change, but writer thread unknown.
	 */
	KCSAN_COUNTER_RACES_UNKNOWN_ORIGIN,

	/*
	 * The access cannot be encoded to a valid watchpoint.
	 */
	KCSAN_COUNTER_UNENCODABLE_ACCESSES,

	/*
	 * Watchpoint encoding caused a watchpoint to fire on mismatching
	 * accesses.
	 */
	KCSAN_COUNTER_ENCODING_FALSE_POSITIVES,

	KCSAN_COUNTER_COUNT, /* number of counters */
};
extern atomic_long_t kcsan_counters[KCSAN_COUNTER_COUNT];

/*
 * Returns true if data races in the function symbol that maps to func_addr
 * (offsets are ignored) should *not* be reported.
 */
extern bool kcsan_skip_report_debugfs(unsigned long func_addr);

/*
 * Value-change states.
 */
enum kcsan_value_change {
	/*
	 * Did not observe a value-change, however, it is valid to report the
	 * race, depending on preferences.
	 */
	KCSAN_VALUE_CHANGE_MAYBE,

	/*
	 * Did not observe a value-change, and it is invalid to report the race.
	 */
	KCSAN_VALUE_CHANGE_FALSE,

	/*
	 * The value was observed to change, and the race should be reported.
	 */
	KCSAN_VALUE_CHANGE_TRUE,
};

enum kcsan_report_type {
	/*
	 * The thread that set up the watchpoint and briefly stalled was
	 * signalled that another thread triggered the watchpoint.
	 */
	KCSAN_REPORT_RACE_SIGNAL,

	/*
	 * A thread found and consumed a matching watchpoint.
	 */
	KCSAN_REPORT_CONSUMED_WATCHPOINT,

	/*
	 * No other thread was observed to race with the access, but the data
	 * value before and after the stall differs.
	 */
	KCSAN_REPORT_RACE_UNKNOWN_ORIGIN,
};

/*
 * Print a race report from thread that encountered the race.
 */
extern void kcsan_report(const volatile void *ptr, size_t size, int access_type,
			 enum kcsan_value_change value_change,
			 enum kcsan_report_type type, int watchpoint_idx);

#endif /* _KERNEL_KCSAN_KCSAN_H */
Commit	Line	Data
dfd402a4 ME	1	/* SPDX-License-Identifier: GPL-2.0 */
	2
	3	/*
	4	* The Kernel Concurrency Sanitizer (KCSAN) infrastructure. For more info please
	5	* see Documentation/dev-tools/kcsan.rst.
	6	*/
	7
	8	#ifndef _KERNEL_KCSAN_KCSAN_H
	9	#define _KERNEL_KCSAN_KCSAN_H
	10
2e986b81	11	#include <linux/atomic.h>
dfd402a4	12	#include <linux/kcsan.h>
92c209ac	13	#include <linux/sched.h>
dfd402a4 ME	14
	15	/* The number of adjacent watchpoints to check. */
	16	#define KCSAN_CHECK_ADJACENT 1
6119418f	17	#define NUM_SLOTS (1 + 2*KCSAN_CHECK_ADJACENT)
dfd402a4	18
2402d0ea ME	19	extern unsigned int kcsan_udelay_task;
	20	extern unsigned int kcsan_udelay_interrupt;
	21
dfd402a4 ME	22	/*
	23	* Globally enable and disable KCSAN.
	24	*/
	25	extern bool kcsan_enabled;
	26
92c209ac ME	27	/*
	28	* Save/restore IRQ flags state trace dirtied by KCSAN.
	29	*/
	30	void kcsan_save_irqtrace(struct task_struct *task);
	31	void kcsan_restore_irqtrace(struct task_struct *task);
	32
dfd402a4 ME	33	/*
	34	* Initialize debugfs file.
	35	*/
	36	void kcsan_debugfs_init(void);
	37
2e986b81 ME	38	/*
	39	* Statistics counters displayed via debugfs; should only be modified in
	40	* slow-paths.
	41	*/
dfd402a4 ME	42	enum kcsan_counter_id {
	43	/*
	44	* Number of watchpoints currently in use.
	45	*/
	46	KCSAN_COUNTER_USED_WATCHPOINTS,
	47
	48	/*
	49	* Total number of watchpoints set up.
	50	*/
	51	KCSAN_COUNTER_SETUP_WATCHPOINTS,
	52
	53	/*
	54	* Total number of data races.
	55	*/
	56	KCSAN_COUNTER_DATA_RACES,
	57
d591ec3d ME	58	/*
	59	* Total number of ASSERT failures due to races. If the observed race is
	60	* due to two conflicting ASSERT type accesses, then both will be
	61	* counted.
	62	*/
	63	KCSAN_COUNTER_ASSERT_FAILURES,
	64
dfd402a4 ME	65	/*
	66	* Number of times no watchpoints were available.
	67	*/
	68	KCSAN_COUNTER_NO_CAPACITY,
	69
	70	/*
	71	* A thread checking a watchpoint raced with another checking thread;
	72	* only one will be reported.
	73	*/
	74	KCSAN_COUNTER_REPORT_RACES,
	75
	76	/*
	77	* Observed data value change, but writer thread unknown.
	78	*/
	79	KCSAN_COUNTER_RACES_UNKNOWN_ORIGIN,
	80
	81	/*
	82	* The access cannot be encoded to a valid watchpoint.
	83	*/
	84	KCSAN_COUNTER_UNENCODABLE_ACCESSES,
	85
	86	/*
	87	* Watchpoint encoding caused a watchpoint to fire on mismatching
	88	* accesses.
	89	*/
	90	KCSAN_COUNTER_ENCODING_FALSE_POSITIVES,
	91
	92	KCSAN_COUNTER_COUNT, /* number of counters */
	93	};
2e986b81	94	extern atomic_long_t kcsan_counters[KCSAN_COUNTER_COUNT];
dfd402a4 ME	95
	96	/*
	97	* Returns true if data races in the function symbol that maps to func_addr
	98	* (offsets are ignored) should not be reported.
	99	*/
5cbaefe9	100	extern bool kcsan_skip_report_debugfs(unsigned long func_addr);
dfd402a4	101
b738f616 ME	102	/*
	103	* Value-change states.
	104	*/
	105	enum kcsan_value_change {
	106	/*
	107	* Did not observe a value-change, however, it is valid to report the
	108	* race, depending on preferences.
	109	*/
	110	KCSAN_VALUE_CHANGE_MAYBE,
	111
81af89e1 ME	112	/*
	113	* Did not observe a value-change, and it is invalid to report the race.
	114	*/
	115	KCSAN_VALUE_CHANGE_FALSE,
	116
b738f616 ME	117	/*
	118	* The value was observed to change, and the race should be reported.
	119	*/
	120	KCSAN_VALUE_CHANGE_TRUE,
	121	};
	122
dfd402a4 ME	123	enum kcsan_report_type {
	124	/*
	125	* The thread that set up the watchpoint and briefly stalled was
	126	* signalled that another thread triggered the watchpoint.
	127	*/
	128	KCSAN_REPORT_RACE_SIGNAL,
	129
	130	/*
	131	* A thread found and consumed a matching watchpoint.
	132	*/
	133	KCSAN_REPORT_CONSUMED_WATCHPOINT,
	134
	135	/*
	136	* No other thread was observed to race with the access, but the data
	137	* value before and after the stall differs.
	138	*/
	139	KCSAN_REPORT_RACE_UNKNOWN_ORIGIN,
	140	};
5cbaefe9	141
dfd402a4 ME	142	/*
	143	* Print a race report from thread that encountered the race.
	144	*/
47144eca	145	extern void kcsan_report(const volatile void *ptr, size_t size, int access_type,
135c0872	146	enum kcsan_value_change value_change,
6119418f	147	enum kcsan_report_type type, int watchpoint_idx);
dfd402a4 ME	148
dfd402a4 ME	149	#endif /* _KERNEL_KCSAN_KCSAN_H */